San Juan: getting around

By taxi - there is a flat-rate system for most destinations within San Juan, which is effective, and if you’re caught in impenetrable traffic, it might actually work to your advantage. It would cost you no more than $20 from the airport to Old San Juan.
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Photo by cabspr.com
  By bus -the Metropolitan Bus Authority operates buses in the greater San Juan area. Bus stops are marked by upright metal signs or yellow posts that say parada. The bus terminal is the dock area in the same building as the Covadanga parking lot next to the Treasury Department. Fares are 75¢. By ferry - the Acuaexpreso ferry connects Old San Juan with the industrial and residential community of Cataño, across the bay. Ferries depart daily every 30 minutes from 6am to 9pm. The one-way fare to Cataño is 50¢.
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Photo by city-data.com
  By public car - called públicos, are either vans or large sedans that are shared by passengers. Though they can be crowded and uncomfortable, more often than not, they are quite comfortable and spacious. And they are a bargain for budget travelers who have to travel a distance from the airport and do not want to rent a car. By bike - Rent the Bicycle, is at the entrance of the Old San Juan bayside waterfront. They rent bikes for $27 per day ($17 for half a day) and also conduct several tours throughout San Juan ($39–$79). The two best are the Piñones and the San Juan city and beach tours. Paradise Rentals rents electric bicycles, or E-bikes, which allow you to decide whether to pedal or not. Three hours costs $50, with each additional hour $15.
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Photo by backroads.com